European Patent Application No. P 82 012 511.1 describes a form of electrical drive pulse control providing two current pulses of different strengths.
German Pat. No. 22 15 519 refers to a method of recording image information on electrosensitive paper, in particular recording metal paper, using a group of individually controllable print electrodes, wherein the on period of each print electrode is selected to be shorter than the time after which the burning process would cease of its own accord. This patent also discloses halftone recording by changing the density such that the selected on period of the individual print electrodes during the burning process is shorter or longer. Finally, German Offenlegungsschrift No. 30 40 153 discloses a method of recording halftones of different brilliance on an electrosensitively coated record carrier by means of print electrodes, wherein the differences in the halftones are generated by modulating the areas of the individual picture elements, and wherein the picture elements are produced by modulating the electric pulses, the duration of the pulses being modulated in the manner disclosed in the aforementioned patent.
In principle, these latter two methods use only one strong current pulse in response to which the arc necessary for burning a mark is invariably struck. Before the end of the burning process, this pulse has to be switched off. However, such methods are poorly suited for extremely high resolutions.